1. Technology Field
The present invention relates to a data reading method for a rewritable non-volatile memory module, a memory control circuit unit using the method, and a memory storage apparatus using the method.
2. Description of Related Art
Digital cameras, mobile phones, and MP3 music players have undergone rapid growth in recent years, so that consumers' demands for storage media have also drastically increased. Since a rewritable non-volatile memory module (e.g., a flash memory) is characterized by data non-volatility, low power consumption, small volume, the non-mechanical structure, and so on, the rewritable non-volatile memory module is suitable for being installed in a variety of portable multimedia apparatuses.
Generally, data written into the rewritable non-volatile memory module are encoded according to an error correcting code, and the data read from the rewritable non-volatile memory module are also decoded by performing the corresponding process. The error correcting ability of the error correcting code is somehow limited. For instance, in a case where the error correcting code is generated by using a block turbo code (BTC) algorithm or a low density parity check (LDPC) code algorithm in an iterative manner, if the number of times of performing the iterative decoding operations is increased to a certain degree, the number of error bits will no longer be reduced together with the number of times of the subsequently performed iterative decoding operations. This is the so-called error floor. Accordingly, how to decode data read from the rewritable non-volatile memory module to acquire correct data is one of the major concerns in the pertinent industry.